Failure in initializing registration due to unescaped user part in account contact

[nanang]

When adding account (using pjsua_acc_add()) with an escaped account ID, e.g: "user%40@some.domain", the account will be successfully added, but soon the registration will fail in initialization stage and unfortunately application will not be informed about this registration failure, i.e: pjsua_acc_add() returns PJ_SUCCESS and PJSUA callback on_reg_state is not invoked.

After investigation, we found that PJSUA will internally store the user part unescaped, e.g: "user@", and later when user part is used for generating Contact header (which is done without escaping), the Contact header will be invalid, e.g: "user@@some.domain".

Thanks Nils Lichtenfeld for the report.

[nanang]

In 5579:

Fixed #2010: Updated PJSUA to store the user part of an account ID in escaped form.